Hair dryers



Aug. 20, 1968 LA|NG 3,397,463

HAIR DRYERS Filed Jan. 3. 1966 9 Sheets-Sheet 1 H69. if? 55/ 2 J44 J55 Zfl/ INVENTOR Nikol us Loing ATTORNEYS Aug. 20, 1968 N. LAING 3,397,463

HAIR DRYEHS Filed Jan. 5. 1966 9 Sheets-Sheet 2 INVENTOR Nikol s Loing avfim w ATTORNEYS N. LAING HAIR DRYERS Aug. 20, 1968 9 Sheets-Sheet 3 Filed Jan. 3, 1966 LL JU U 3 500335 FIG] 4 INVENTOR Nigalous Loing M, W z 4 7 ATTORNEYS Aug. 20, 1968 N. LAING HAIR DRYERS Filed Jan. 5, 1966 FIGJZ.

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Illlllllllllllllllllllil lllllllllllllllllillll I ll 9 Sheets-Sheet 4 INVENTOR Nikolaus Lcing Y M, WN/CA, 4 TORNEYS Aug 20, 1968 N. LAING 3,397,463

HAIR DRYERS Filed Jan. 5. 1966 9 Sheets-Sheet 5 1m F/G.75. 41/ 45/ INVENTOR ATTORNEYS Nikolaus Loin 9 Sheets-Sheet 6 N. LAING HAIR DRYERS INVENTOR Nbolous Lain v Mi -vi f Aug. 20, 1968 Filed Jan. 3, 1966 F/GJ7.

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N. LAING HAIR DRYERS Aug. 20, 1968 9 Sheets-Sheet 7 Filed Jan. 3, 1966 WWW R E E S T m Aug. 20, 1968 Filed Jan. 1966 N. LAING HAIR DRYERS 9 Sheets-Sheet 9 F/G.25,. 455 My 471 I 474 INVENTQR Nlkolous Lcung- Y I, /2M,:, ATTORNEYS United States Patent 3 Claims. (Cl. 34-97) ABSTRACT OF THE DISCLOSURE A portable hand-held hair dryer having a casing with a long rectangular outlet, a cross-flow type blower in the casing at an end opposite the outlet and extending parallel to the outlet, and electric heater means in the casing positioned between the cross-flow blower and outlet.

This invention relates to portable hair dryers, that is, small electrically driven blowers provided with electric heater means and made so that the user can hold the blower in the hand to direct the stream of warmair against the hair as may be required.

The application is a continuation-in-part of my copending application No. 221,621 filed September 5, 1962, now Patent No. 3,232,522, which is itself a continuationin-part of my now abandoned application No. 671,114, filed July 5, 1957.

Hitherto commercially available types of portable hair dryer have normally utilized centrifugal blowers, i.e., where the rotor takes in air axially and discharges it radially into a scroll leading to an outlet duct. In one common form of such hair dryer a casing surrounds the rotor and provides the outlet duct and a housing for the motor at one side: a handle forming part of the casing or attached to it extends in the general plane of the rotor, generally at a right angle to the outlet. For application to hair dryers the centrifugal blower has many disadvantages. Firstly, without sacrifice of efiiciency the outlet duct area can only be square or circular in section, or approximately so, because of the design limitations inherent in centrifugal blowers; that is, since the air has to enter the rotor axially the length of the rotor cannot usefully exceed a certain proportion of its diameter-about 0.6 for a single-inlet rotor and 1.2 for a rotor with inlets at both ends. This, coupled with the fact that the centrifugal fan is an inherently bulky device for a given air flow and rotor speed, has led to the use of rather large centrifugal rotors, so that the common form of hair dryer referred to is somewhat cumbersome. Moreover in this form of hair dryer the outlet duct, handle and motor housing commonly extend in mutually perpendicular directions so that the hair dryer is awkward to pack and store.

The general object of the present invention is to provide a new form of portable hair dryer which is free from the disadvantages of the hair dryer just described. The hair dryer according to the invention makes use of a particular form of blower, called herein a cross-flow blower, comprising a bladed cylindrical rotor defining an interior space and mounted for rotation about its axis in a prede termined direction, and guide surfaces extending the length of the rotor in spaced relation exteriorly thereto and co-operating with the rotor on rotation thereof in said predetermined direction to induce a flow of air from one side of the rotor through the path of the rotating blades thereof to said interior space and thence again through the path of the rotating blades to another side of the rotor.

In one aspect, the invention provides a particularly compact form of portable dryer comprising a casing with an inlet and a long rectangular outlet and including a rear wall opposite the outlet with a concave interior surface, and a bottom wall into which the rear wall merges and which extends to the outlet; the bladed cylindrical rotor is located within the casing adjacent the rear wall opposite the outlet and parallel to the length thereof, the length of the outlet being at least the major part of the length of said rotor; means including an electric motor are provided for mounting the rotor for rotation about its axis the motor driving the rotor in a predetermined direction; the appliance further comprises a second wall presenting to the rotor means a guide surface opposite the rear wall and extending from the rotor to the outlet opposite the bottom wall, said second wall and bottom wall defining an outlet duct leading from the rotor to the outlet; the guide surface of the second wall and the interior surface of the rear wall (which form the guide surfaces referred to in the preceding paragraph) co-operate with the rotor on rotation thereof to induce a flow of air from the inlet through the rotor as described, and through the outlet duct, where heater means are located, to the outlet; the outlet duct is shaped to have the effect of a convergent nozzle upon heated air flowing through the outlet whereby said air leaves the outlet as a flat jet. (It is not absolutely necessary that the outlet duct should converge, though preferably it will do so: the effect of a convergent nozzle, and the consequent emission of air in the form of a jet, could be achieved, bearing in mind the expansion of the air on heating, if the duct was slightly divergent provided the duct cross section increased less than the air volume.) In principle the length of the rotor means can be extended indefinitely since flow therethrough does not depend on axial inflow thereto as in a centrifugal blower but takes place substantially in paths at right angles to the rotor axis. Thus the design of the outlet shape is unfettered by any consideration of flow principle, and can have a length several times its breadth. Advantageously, the outlet has the form of a flat nozzle which may be convergent. By lengthening the rotor, its throughput can be increased without increase of diameter, thus providing a compact construction. The rotor diameter can in fact be kept low by the use of a commutator motor which revolves much faster than the induction motor commonly employed in the conventional form of hair dryer alluded to earlier: noise is no problem since the cross-flow blower even at high speed can be made relatively quiet, at least within tolerable limits.

As will be appreciated from the foregoing the invention proposes to make use of the casing rear and bottom walls to provide guide surfaces for co-operation with the rotor means and one wall of the outlet duct. In one preferred construction the second wall also forms part of the top wall of the casing. The inlet is preferably an taperture d area in the top wall of the casing, the apertured area extending substantially the length of the rotor means and from the rear 'wall forwardly to subtend an angle of substantially more than at the axis of the rotor means. By providing large-area-inlet, which is hard to arrange with a centrifugal fan, the inlet air velocity is reduced and there is consequently less tendency for stray hairs to be sucked into the inlet.

The appliance which the invention provides has another advantage that according to a further feature of the invention the motor can conveniently be enclosed in an endwise extension of the casing which can be formed as a hand grip; the invention contemplates also that this feature may be used in appliances which, though using crossfiow blowers, do not have all the features above mentioned. Alternatively the casing may carry a handle pivotable thereon 'between an operative position and a position in which it is folded back against the casing. Either way the appliance can be given a simple slab-like form, or a somewhat tubular 'form with a slight projection, which contrasts with the awkwardness of the prior construction mentioned above.

In a further aspect the invention provides a hair dryer with a casing containing the rotor and defining an inlet and a generally longitudinally row of nozzle-like outlets, the rotor being positioned directly opposite the row. and extending over the length thereof, the nozzle-like outlets being directed away from the rotor. The nozzle-like outlets can be used in the manner of a comb to direct the warm air towards the roots of the hair and thereby promote rapid drying.

Further features, objects and advantages of the invention will be apparent from the following description of certain embodiments of the invention. In the accompanying diagrammatic drawings:

FIGURE 1 is a cross-sectional view of a blower illustrating the design principles which it is preferred to apply in carrying out the invention;

FIGURE 2 is a graph illustrating air velocity at the outlet of a blower such as that of FIGURE 1;

FIGURE 3 is a graph illustrating air velocity at the outlet of a conventional blower;

FIGURE 4 is a graph illustrating the velocity of air flow within the field and core of a Rankine vortex;

FIGURE 5 illustrates the ideal flow occurring in one half the cross-sectional area of a rotor such as shown in FIGURE 1;

FIGURE 6 is a vector diagram illustrating the flow of air over a blade of the FIGURE 1 rotor from the interior of the rotor to the exit side thereof;

FIGURE 7 is a longitudinal section, with part cut away, of a hair dryer according to the invention, having a long slot-like outlet with part of the handle shown in elevation;

FIGURE 8 is a cross-section of the FIGURE 7 hair dryer taken on the line VIII-VIII of that figure;

FIGURE 9 is a longitudinal section of a second form of hair dryer according to the invention, which is generally similar to that of FIGURE 7 except that instead of a slot-like outlet it has a row of nozzle-like openings;

FIGURES 10 and 11 are respectively a longitudinal section and a cross-section of a third form of hair dryer according to the invention, the cross-section being taken on the line XIXI in FIGURE 10;

FIGURE 12 is a top plan view of a fourth form of hair dryer according to the invention having features in common with that of FIGURES 7 and 8;

FIGURES 13 and 14 are cross-sectional views of the FIGURE 12 hair dryer taken on the lines XIH--XIII and XIVXIV respectively in that figure;

FIGURE 15 is a top plan view of a fi-f-th form of hair dryer with portions cut away to show interior parts, this hair dryer again having affinities with that of FIGURES 7 and 8;

FIGURE 16 is a cross-section of the FIGURE 15 hair dryer taken on the line XVIXVI in that figure;

FIGURE 17 is a longitudinal section through a sixth form of hair dryer having features in common with that of FIGURES 12 to 14 but having a handle pivotable between operative and inoperative positions, this figure showing the handle in the former position;

FIGURE 18 is a view of the sixth form of hair dryer showing the handle pivoted to inoperative position;

FIGURE 19 is a cross-section of the hair dryer of FIGURES 17 land 18 taken on the line XIX-XIX of FIGURE 17;

FIGURE 20 is a view similar to FIGURE 17 and showing a variant of the sixth form of hair dryer;

FIGURE 21 is a plan view of a further modification of the hair dryer of FIGURES 17 to 19 which modification employs difierent handle pivoting arrangement and is designed to make use of an internal component comprising in one structure fan rotor, motor, flow guide and heater; I

FIGURES 22 and 23 are elevations of the FIGURE 21 hair dryer seen in the direction of the arrow XXII and XXIII in that figure and showing the handle in operative and inoperative positions respectively;

FIGURE 24 is a cross-sectional view of the FIGURE 21 hair dryer taken on the line XXIVXXIV in that figure, and

FIGURE 25 is a plan view of the component above referred to of the FIGURE 21 hair dryer;

FIGURE 26 is a circuit diagram showing the electrical connections of the motor and heater of previous embodiments.

Referring to the drawings before discussing the preferred form of hair dryers according to the invention shown in FIGURES 7 to 25, the principles of blower design which they incorporate will first be discussed with reference to FIGURES 1 to 6.

'The FIGURE 1 blower comprises a cylindrical bladed rotor 2 having thereon a plurality of blades 3 concavely curved in the direction of rotation of the rotor indicated by the arrow 4 wherein the blades 3 have their outer edges 5 leading their inner edges 6. The outer edges define an outer envelope 7 while the inner edges define an inner envelope 8 when the rotor is rotated. The rotor is mounted, by means not shown, whereby it will rotate about its axis. A guide wall 9 extends the length of the rotor and merges with a wall 10 to form one side of an exit duct 11 of the machine. A vortex-forming and stabilizing means 12 also extends the length of the rotor and is positioned exteriorly thereof and has thereon a wall 13 which forms part of the exit duct and which more particularly forms part of a diffuser section 14 as is more fully explained hereafter.

The vortex-forming and stabilizing means 12 has a rounded end 15 which has a portion extending towards the rotor in the direction of rotation to form a converging gap 16 which, as more fully explained hereafter, serves to form and stabilize a fluid vortex when the rotor is rotated. The means 12 also serves to separate the suction side S from the pressure side P of the machine and defines with the wall 9 an entry and an exit region to the rotor. End walls 19, only one of which is shown, substantially cover the ends of the machine.

The wall 9 terminates at point 20 which is spaced from the rotor at minimum of one-third the blade depth and not more than three times the blade depth of the blades 3 in order to minimize interference which causes an undesirable noise when the machine is operated while at the same time the wall provides a means to guide the flow leaving the machine. Wall 15 of the vortex-forming and stabilizing means 12 likewise is spaced a substantial distance from the rotor, in this instance a distance equal to a minimum distance of at least one-third the blade depth of the blades of the rotor. Because both the wall 9 and the vortex-forming and stabilizing means 12 are spaced from the latter a substantial distance, close manufacturing tolerances do not have to be observed when assembling the machine and, as such, the machine lends itself to economical construction such as is achieved when sheet metal stampings are utilized.

In operation of the blower illustrated in FIGURE 1, a fluid vortex having a core designated by the line V approximating a Rankine type vortex is formed wherein the core is positioned eccentrically with respect to the rotor axis and wherein the core will interpenetrate the path of the rotating blades of the rotor. The whole throughput of the machine will then flow twice through the blade envelope in a direction perpendicular to the rotor axis as indicated by the flow lines F, MF.

FIGURE 4 illustrates an ideal relation of the vortex to the rotor 2 and the distribution of flow velocity in the vortex and in the field of the vortex. The line 40 represents a part of the inner envelope 6 of the rotor blades 3 projected onto a straight line while the line 41 represents a radius of the rotor taken through the axis of the vortex core V. Velocity of fluid at points on the line 41 by reason of the vortex is indicated by the horizontal lines 43a, 43b, 43c and 4311, the length of these lines being the measure of the velocity at the points 43a 43b 43c and 4311 The envelope of these lines is shown by the curve 44 which has two portions, portion 44a being approximately a rectangular hyperbola and the other portion, 441;, being a straight line. Line 44a relates to the field region of the vortex and the curve 44b to the core. It will be understood that the curve shown in FIGURE 4 represents the velocity of fluid where an ideal or mathematical vortex is formed, and that in actual practice flow conditions will only approximate these curves.

The core of the vortex is a whirling mass of fluid with no translational movement as a whole and the velocity diminishes from the periphery of the core to the axis 42. The core of the vortex intersects the blade envelope as indicated at 40 and an isotach I within the vortex having the same velocity as the inner envelope contacts the enevolpe. The vortex core V is a region of low pressure and the location of the core in a machine constructed according to the invention can be determined by measurement of the pressure distribution Within the rotor.

The velocity profile of the fluid where it leaves the rotor and passes through the path of the rotating blades will be that of the vortex. In the ideal case of FIGURE 4, this profile will be that of the Rankine vortex there shown by curves 43a and 43b, and in actual practice, the profile will still be substantially that shown in FIGURE 4 so that there will be in the region of the periphery of the core V shown in FIGURE 1 a flow tube MP of high velocity and the velocity profile taken at the exit of the rotor will be similar to that shown in FIGURE 2 where the line FG represents the exit of the rotor and the or- 'dinates represent velocity. The curve shown exhibits a pronounced maximum point C which is much higher than the average velocity represented by the dotted line.

It will be appreciated that much the greater amount of fluid flows in the flow tubes in the region of maximum velocity. It has been found that approximately 80% of the flow is concentrated in the portion of the output represented by the line AE which is less than 30% of the total exit of the rotor. A conventional velocity profile for fluid flow in a defined passage is illustrated by way of contrast in FIGURE 3 where the average velocity of flow is represented by the dotted line. Those skilled in the art regard this profile as being approximately a rectangular profile which following the principle generally adhered to is the sort of profile heretofore sought in the outlet of a flow machine.

The maximum velocity C shown in FIGURE 2 appertains to the maximum velocity flow tube indicated as MP in FIGURE 1. With a given construction the physical location of the flow tube MF may be closely defined. The relative velocity between the blades and fluid in the restricted zone of the rotor blades 3 through which the flow tube MF passes is much higher than it would be if a flow machine were designed following the conditions adhered to heretofore in the art respecting the desirability of a rectangular velocity profile at the exit arc and even loading of the blades.

flow tubes are considered, there is a substantial gain in efliciency.

FIGURE 5 illustrates the ideal distribution of flow tubes F occurring within one half the rotor area defined by the inner envelope 6, it being understood that the flow tubes in the other half of the rotor are similar. The maximum velocity flow tube MF is shown intersecting the envelope 6 at point 50 and the isotach I as being circular when the whole rotor is considered. It is seen that ideally the maximum velocity flow tube MF undergoes a change of direction of substantially 180 from the suction to the pressure sides when the flow in the whole rotor is considered. It is also to be noted that the major part of throughput, represented by the flow tube MF, passes through the rotor blades where they have a component of velocity in a direction opposite to the main direction of flow within the rotor indicated by the arrow A.

FIGURE 6 is a diagram showing the relative velocities of flow with respect to a blade at the point 50 referred to in FIGURE 5. In this figure V represents the velocity of the inner edge of the blade 3 at the point 50, V the absolute velocity of the air in the flow tube MF at the point 50, and V the velocity of that air relative to the blade as determined by completing the triangle. The direction of the vector V coincides with that of the blade at its inner edge so that fluid flows by the blade substantially without shock.

The character of a vortex is considered as being determined largely by the blade angles and curvatures. The position of the vortex, on the other hand, is considered as being largely determined by the configuration of the vortex forming means which forms and stabilizes a vortex in co-operation with the bladed rotor. The particular angles and curvatures in any given case depend upon the following parameters: the diameter of the rotor, the depth of a blade in a radial direction, the density and viscosity of the fluid, the disposition of the vortex forming means and the rotational speed of the rotor, as well as the ratio between over-all pressure and back presure. These parameters must be adapted to correspond to the operating conditions in a given situation. Whether or not the angle and shape of the blades have been fixed at optimum values is to be judged by the criterion that the flow tubes close to the vortex core are to be deflected substantially greater than It is to be appreciated that the flow lines of FIGURE 1 do not correspond exactly to the position of the vortex core V as illustrated in FIGURES 4 and 5 which represent the theoretical or mathematical flow. These latter figures show that it is desirable to have the axis of the core of the vortex within the inner blade envelope 6 so that the isotach within the core osculates that envelope. Although this position is achieved in certain constructions hereinafter described, it is not essential, and in fact, is not achieved in the structure shown in FIGURE 1.

It is to be further appreciated that despite the divergence of the flow in FIGURE 1 from the ideal, the maximum velocity flow tube MF with which is associated the major part of the throughput is nevertheless turned through an angle of substantially in passing from the suction to the pressure side of the rotor and that this maximum flow tube passes through the rotor blades where the blades have a velocity with a component opposite to the main direction of flow through the rotor as indicated by the arrow A.

The portable hair dryer shown in FIGURES 7 and 8 is to be regarded as incorporating the teaching of FIG- URE'S 1 to 6, despite certain variations in the shape and arrangement of its parts. The hair dryer comprises a bladed cylindrical rotor 2 similar to that of FIGURE 1 and having disc-like end members 300, 301: other parts of the rotor resemble those of FIGURE 1 and are similarly designated. The hair dryer has a handle 330 having an extension or shroud 331 of sheet material.

The handle 330 and shroud 331 are coaxial with the rotor 2 which has one end member 300 mounted on and driven by the shaft 332 and an electric motor 333 (which as shown is of commutator type) mounted coaxially in the handle and the other end member 331 rotatably supported by a bearing 332a at the end of the shroud remote from the handle. Vortex forming and stabilizing means 334 (including parts of the shroud 331 adjacent the rotor and an auxiliary body 334a), performs the same function as the means 12 in FIGURE 1 in that on rotation of the rotor a vortex having a core V is set up and stabilized. The shroud 331 also has generally converging outlet walls 335 and 336 between which are mounted a heater coil 337 in order to heat air passing thereover. These walls converge going in the direction of flow to a slot-like outlet 339 extending the length of the rotor. The wall 335 includes a concave portion 335a extending around the rotor to the inlet and performing the function of the wall 9 in FIGURE 1.

In a modification of the hair dryer of FIGURES 7 and 8, which modification is shown in FIGURE 9, the flat nozzle-like outlet 339 is replaced by a row of nozzle-like outlets 340 located directly opposite to and directed away from the rotor 2. The nozzle-like outlets 340 form a coarse comb, and enable warm air to be discharged close to the head below the level of the hair, so as to promote rapid drying.

A further embodiment of a portable hair dryer is shown in FIGURES 10 and 11, which once again includes a rotor 2 and guide means as described with reference to FIGURES 1 to 6.

The device comprises a handle 360 having a short coaxial shroud 361 of comparatively large diameter. An electric motor 362 is mounted in the handle coaxially therewith and drives the rotor 2 which is located coaxially within the shroud; the rotor is closed at the motor end by a disc 364 which supports the blades 365 of the rotor and which is secured on the end of the motor shaft 364a. The other end of the rotor is substantially closed by the end wall 366 which is secured to the shroud and which supports therein a plurality of heater coils 367. The rotor 2 and adjacent guide surfaces of the shroud 361 co-operate in the manner described with reference to FIGURES 1 to 6 to set up a flow through the inlet 369, twice through the path of the rotating blades 365 of the rotor in a direction transverse to the rotor axis and out through outlet 368. Although the heater coils 367 obstruct to some extent the free flow of air through the rotor 2, the construction shown has the advantage in that the heater elements are protected without the inclusion of separate special housing means.

A fourth form of portable hair dryer is illustrated in FIGURES 12 to 14, and comprises a casing designated generally 400 within which is mounted a cylindrical bladed rotor 401 and electric heater element 402 which will be further described, and which has an endwise extension 403 containing a motor 404 of the commutator type which drives the rotor, and a press-button control switch 405.

The casing 400 which is conveniently made in plastics material, possibly as a two-part interfitted moulding, has end walls 406, 407; a concave rear wall 408 merging with a nearly flat bottom wall 409 extend between the end walls together with a top or second wall 410. The rotor 401 comprises a series of similar blades 411 extending between supporting end discs 412 (one only of which is seen in FIGURE 12) and is generally similar to the rotor illustrated in FIGURE 1. The rotor 401 has one end disc 412 supported on one end of the spindle (not shown) of the motor 404 and its other end supported by a stub shaft and bearing (not shown) in the opposite end wall 407 of the casing. The rotor 401 is located adjacent the rear casing wall 408 so as to be embraced thereby. The rear wall 408 and the top wall 410 define between their lines of nearest approach 413, 414 to the rotor 401 an inlet 415 to the casing 400 extending the length of the rotor and over an arc thereof substantially greater than A series of deep but narrow vanes 416 extending in spaced planes perpendicular to the rotor axis over the inlet 415, joining the top and rear casing walls 410, 408. These vanes 416 protect the rotor 401 from possible contact with the users hand and at the same time (ensure that if the users hand is over'the inlet air can still flow therethrough into the casing. The top and bottom walls 410, 409 of the casing 400 with the end walls 406, 407 define an outlet 417 of long rectangular shape extending parallel to and opposite the rotor 401, and a" wide and slightly convergent outlet duct 418 leading from the rotor 401 to the outlet. The heater element 402 is located in the outlet duct 418 and comprises three insulating rods 419 (eg of steatite) extending parallel to the rotor axis between the end walls 406, 407 and a resistor wire 420 wound about the rods and located in grooves 421formed therein. Varies 422 extend across the outlet 417 toprevent a users finger from accidentally coming into contact with the heater element. 1

The top wall 410 comprises a portion 423 facing the rotor 401, subtending a small angle (under 30) at the axis of the rotor, and defining therewith a gap 424 which in this instance converges with the rotor in the direction of rotation thereof, shown by the arrow 424. The portion 423 of the top wall 410 meets the main portion 425 thereof defining the outlet duct 418 in a rounded nose 426, the portions 423 and 425 defining thereat an angle just slightly in excess of a right angle. The top wall 410 and rear wall 408 are spaced by a large clearance from the rotor at their lines 414, 413 of nearest approach: a clearance of at least half the radial depth of the rotor blades 411 is preferred; this clearance is found to improve efficiency, reduce noise and facilitate manufacture by obviating the need to maintain close tolerances. The guide means, comprising the casing walls 410 and 408, co-operate with the rotor 401 on rotation thereof in the manner described in detail with reference to FIGURES 1 to 6 and set up a vortex of Rankine type having a core region designated V which interpenetrates the rotor blades adjacent the wall portion 423, and guiding flow through the rotor as shown by the arrows F. In passing through the rotor 401 flow entering the rotor from above is turned through an angle exceeding 90 and directed straight through the outlet duct 418 past the heater element 402 therein. The duct 418 is slightly convergent in form, but has the effect of a rather strongly convergent nozzle by reason of the heating of the air which takes place due to the element 402. The air therefore emerges from the outlet 417 at considerable velocity.

The user grips the hair dryer around the casing extension 403, and possibly with some part of his hand around the casing 400 itself. As has been explained, the vanes 416 prevent the hand from blocking the inlet. The motor 405 is the heaviest part of the hair dryer, and the centre of gravity of the hair dryer will therefore lie close tothe users hand. I

Resemblances will be noted between the hair dryer of FIGURES 7 and 8 and that of FIGURES 12 to 14. Thus in each there is an outlet 339, 417 respectively which is relatively long (i.e., the dimension parallel to the rotor axis) in relation to its width..In each there is, opposite the outlet, a rear wall with a concave interior surface, respectively the wall portion 335a and the wall 408, which merges vn'th a bottom wall extending to the outlet, being the remainder of wall 335 and wall 409 respectively. The rotor 2, 401 lies adjacent the rear wall and embraced thereby, and is parallel and directly opposite to the outlet. -In each case a second wall 334, 335 and 410 respectively presents to the rotor a guide surface opposite the rear wall and extends to the outlet and defines with the bottom wall an outlet duct leading from the rotor to the outlet and having the effect of a convergent nozzle. The guide surface -of the second wall andthe rear wall form guide means co-operating with the rotor on rotation thereof .to induce a flow of air from an inlet immediatelyabove the rotor, twice through the path of the rotating blades of the rotor to the outlet duct, past a heater element 337, 402 therein to the outlet, the air being turned by the rotor through an angle of at least 90. Important differences between the two embodiments will also be noted.

The fifth form of hair dryer shown in FIGURES 15 and 16 is a variant of that illustrated in FIGURES 12 to 14; similar parts are designated by the same numerals, and will not need further description. The main differences lie in the casing extensions 403, which here is enlarged to form a conventional handle, and in the heater element which comprises a helically coiled resistance wire 430 which is wound helically about two resistor rods 43-1 extending parallel to the rotor axis within the outlet duct 418 and located in grooves 432 in the rods: the rods are large enough to prevent the coils touching where (as seen in plan, FIGURE 15) they cross. The duct 41-8 is enlarged at 433 to accommodate the element. It will not be necessary to detail the various differences between the hair dryer of FIGURES 15 and 16 and that of FIGURES 12 to 14 which reside only in the relative dimensions of the parts.

Further forms of hair dryer according to the invention, shown in FIGURES 17 to 24, are provided with a handle which can fold against the casing; in this way it i possible, in use, to have the advantages of a handle while for storage or packing the hair dryer has a compact block-like form.

Referring first to FIGURES 17 to 19, the hair dryer there shown has many features similar to that of FIG- URES 12 to 14 and the same reference numerals will be used for generally similar parts which will accordingly not require further description. Before dis-cussing the pivoting handle feature two further main differences between the hair dryer of FIGURES 17 to 19 and that of FIG- URES 12 to 14 will be noted.

Firstly, the heating element 402 has the form of a thin plate of insulating material 440 extending over the area of the outlet duct 418 midway between top and bottom casing walls 410, 409 so as to minimise disturbance to flow, which takes place above and below the plate. A coiled resistor wire 441 is wound helically around the plate, the successive turns being located in notches 442 in the edges of the plate. The successive turns are held midway between the edges by being sewn to the plate with heatresisting insulating thread 443, such as glass thread, which passes through holes 444 in the plate.

Secondly, the armature 445 of the commutator motor 404 is assembled as a single unit with the rotor 401 and mounted in bearings 446, 447, one in the end wall 407 and the other in the opposite wall 448 of the casing extension 403, which is thickened. This wall 448 also mounts the brushes 449 of the motor which co-operate with the commutator 450 and are accessible by removing the end screws 451.

Turning now to the handle, designated 452, it will be seen that this is pivoted to the casing extension 403 at its rear corner about a vertical pin 453. Near the pivot pin 453 the handle is hollow, as shown at 454. Remote from the pin the handle is thickened as shown at 455 and the electrical lead 456 passes through this thickened portion. In use the handle 452 is brought to the position shown in FIGURE 17, and enables easy manipulation of the hair dryer without danger of the users hand blocking the air inlet 415: the flex passes through the users hand so that it cannot interfere with easy manipulation, For packing or storage the handle 452 is brought against the side of the casing as shown in FIGURE 18. The hollow part 454 of the casing encloses and protects the casing extension 403 and the brush end screws 451, while the part 455 fits in the space adjacent to it and lies against the casing end wall 406.

A modification of the arrangement of FIGURES 17 to 19 is shown in FIGURE 20, where the handle 452 is pivoted about a vertical pin 457 mounted in lugs 458 on the outside of the casing end wall 456 adjacent the outlet 417. Once again the handle has a hollow portion 459 enclosing and protecting the casing extension in the closed position of the handle.

A further handle arrangement is shown in the hair dryer of FIGURES 21 to 24. Here, as best shown in FIGURES 21 and 22 the handle 452 is mounted at the same corner of the casing as in FIGURE 20, on a vertical pivot screw 460, but is generally channel-shaped to fold over the outlet 417; the handle is shown in its closed position in FIGURE 23.

The hair dryer of FIGURES 21 to 24 exhibits a construction different from that of previously described embodiments of the invention in that the casing 400 is a simple moulding in two-parts 461, 462 which fit around and locate a sub-unit, designated generally 463 and illustrated alone in plan in FIGURE 25, the sub-unit carrying all the internal parts.

Referring more especially to FIGURES 24 and 25, the sub-unit 463 comprises a wall member 464 moulded in plastics material similar in general configuration to and performing the same function as the top casing wall 410 of FIGURES 12 to 14: the reference numerals given to the parts of the wall member 464 are the same as used for similar parts in FIGURE 13 and will need no further description. The heating element 402 is mounted directly on the wall member 464 and comprises a series of spring wires 465 embedded in the plastics and mounted in two rows, one along the nose 426 and one near the outlet 417, and a coiled resistance wire 467 running to and fro in zig-zag manner between the spring wire 465 of the two rows, and supported and tensioned thereby. At both ends the wall member 464 mounts integral end walls 468, 469 and, between them, the outlet-protecting vanes 422, formed as a series of projections. One end wall 468 has an extension 470 mounting a bearing 471 and the stator 472 of the motor 404. The other end wall 469 has an extension 473 mounting a bearing 474. The motor armature and rotor 401 are combined as a single unit and mounted between the bearings 471, 474.

FIGURE 26 illustrates a circuit arrangement which may be used in any of the embodiments described above. In this circuit the motor is designated M, including an armature A and field winding F in series. The motor M is preferably designed for a voltage which is a fraction only of the full mains voltage, for example 12 volts. The heater is divided into a larger part H controlled by a switch S and a smaller part H both are connected across full mains voltage and the larger dissipates some of the total heater wattage and the smaller dissipates the remainder. The smaller heater part H is divided into two unequal parts I1 h in series to form a voltage dropper or potential divider, and giving a voltage drop over the part 11 which is equal to the designed motor voltage, 12 volts in the example given. The heater part H is used as a voltage dropper, the motor being connected across the portion h only.

I claim:

1. An appliance comprising: a casing having an inlet and a long rectangular outlet and including a rear wall opposite the outlet with a concave interior surface, and a bottom wall into which the rear wall merges and which extends to the outlet; bladed cylindrical rotor means defining an interior space and located within the casing adjacent the rear wall opposite the outlet and parallel to the length thereof, the length of the outlet being at least the major part of the length of said rotor means; means including an electric motor mounting the rotor means for rotation about its axis, the motor driving the rotor in a predetermined direction; a second wall presenting to the rotor means a guide surface opposite the rear wall and extending from the rotor to the outlet opposite the bottom wall with a portion of the guide surface being spaced from the rotor to form an unobstructed gap through which a part of the flow from said outlet may be returned towards said inlet to form and stabilize a fluid vortex, said second wall and bottom wall defining an outlet duct leading from the rotor to the outlet; electric heater means in said outlet duct, the second wall guide surface and rear wall interior surface cooperating with the rotor means upon rotationthereof by the motor to induce a flow of air from the inlet through the path of the rotating blades of the rotor means to said'interior space'and thence again through the path of the rotating blades to the outlet duct, past the heater means and out of the outlet duct, the outlet duct being shaped to have the effect of a convergent nozzle upon heated air flowing through the outlet duct whereby said air leaves the outlet as a flat jet, and the motor, rotor means and heater means being mounted on the second Wall to form a subunit inserted into the casing. 2. An appliance comprising: a casing having an inlet and a long rectangular outlet and including a rear wall opposite the outlet with a concave interior surface, and a bottom wall into which the rear wall merges and which extends to the outlet; bladed cylindrical rotor means defining an interior space and located'within the casing adjacent the rear Wall opposite the outlet and parallel to the length thereof, the length of the outlet being at least the major part of the length of said rotor means; means including an electric motor mounting the rotor means for rotation about its axis, the motor driving the rotor in a predetermined direction; a second wall presenting to the rotor means a guide surface opposite the rear Wall and extending from the rotor to the outlet opposite the bottom wall with a portion of the guide surface being spaced from the rotor to form an unobstructed gap through which a part of the flow from said outlet may be returned towards said inlet to form and stabilize a fluid vortex, said second wall and bottom wall defining an outlet duct leading from the rotor to the outlet; electric heater means in said outlet duct, the second wall guide surface and rear wall interior surface cooperating with the rotor means upon rotation thereof by the motor to induce a flow of air from the inlet through the path of the rotating blades of the rotor means to said interior space and thence again through the path of the rotating blades to the outlet duct, past the heater means and out of the outlet duct, the outlet duct being shaped to have the effect of a convergent nozzle upon heated air flowing through the outlet duct whereby said air leaves the outlet as a flat jet, and the rotor means being a unitary structure having one end mounted on the rotor shaft wherein the motor is mounted upon an end-wise extension of the second wall and the other end of the rotor is mounted on a bearing at the opposite end of the second wall, the second wall also carrying the heater means and said second wall, motor, rotor means and heater means forming a subunit inserted into the casing. I

. 3. An appliance comprising: a casing having an inlet and a long rectangular outlet and including a rear wall opposite the outlet with a concave interior surface, and a bottom wall into which the rear wall merges and which extends to the outlet; bladed cylindrical rotor means defining an interior space and located within the casing adjacent the rear wall opposite the outlet and parallel to thele'ngth thereof, the length of the outlet being at least the major part of'the length of said rotor means; means including an electric motor mounting the rotor means for rotation about its axis, the motor driving the rotor in-a predetermined direction; a second wall presenting to the rotor means a guide surface opposite the rear wall and extending from the rotor to'the outlet opposite the bottom w'all with a portion of the guide surface being spaced from the rotor to form an unobstructed gap through which a part of the flow from said outlet may be returned towards said inlet to form and stabilize afluid vortex, said second wall and bottom wall defining an outlet duct leading from the rotor to the outlet; electric'heater means in said outlet duct, the second wall guide surface and rear wall interior surface cooperating with the rotor means upon rotation thereof by the motor to induce a flow of air from the inlet through the path of the rotating blades of the rotor means to said interior space and thence again through the path of the rotating blades to the outlet duct, past the heater means and out of the outlet duct, the outlet duct being shaped to have the effect of a convergent nozzle upon heated air flowing through the outlet duct whereby said air leaves the outlet as a flat jet, and a handle pivoted adjacent one end of the outlet to collapse thereover when in a nonoperative position and to extend end-wise of the casing when in an operative position.

References Cited UNITED STATES PATENTS 507,445 10/1893 Mortier 230- 1,867,807 7/1932 Campbell 219370 1,920,952 8/1933 Anderson. 2,008,183 7/1935 McCord 219-371 2,027,605 1/ 1936 McCord 219-369 X 2,478,559 8/1949 Bergeron 34243 X 2,591,669 4/ 1952 Bucknell et al. I 2,713,627 7/ 1955 Kamataris. 3,132,232 5/1964 Freedman et al. 34-243 -X 3,232,522 2/l966 Laing 230-125 3,284,611 11/1966 Laing 230-125 FOREIGN PATENTS 1,091,797 11/1954 France.

943,767 12/ 1963 Great Britain.

955,965 4/1964 Great Britain.

428,193 12/ 1947 Italy.

FREDERICK L. MATTESON, JR., Primary Examiner.

A. D. HERRMANN, Assistant Examiner. 

